The present invention relates to an apparatus and process for disintegrating a fiber agglomerate, in particular a fiber agglomerate made of ceramic fibers.
Raw ceramic fibers are often delivered by the supplier of the ceramic fibers in a severely matted condition, i.e. as a fiber agglomerate. In order to further process the fiber agglomerate, the fiber agglomerate must be disintegrated such that the fibers are separated. Furthermore, non-fibrous components and impurities must also be separated from the fiber agglomerate. Fibers which may need to be treated in this manner are, for example, mineral fibers, rock fibers, slag wool, glass fibers, and ceramic fibers. The fibers may have a length, for example, of a magnitude ranging from 0.1 to 0.5 mm.
Fibers of the above-mentioned type are used, for example, to reinforce diesel engine pistons made of light metals. It has been found that, if the fibers are not suitably disintegrated, the non-fibrous coarser particles, hereafter referred to as shot particles, will remain between the fibers. This may have an extremely negative impact on a component, in the above example a diesel engine piston, that is to be reinforced with the fibers.
Fibers of the above-mentioned type are also used for furnace linings. In gas-heated furnaces, in which high flue gas rates occur, shot particles can dissolve out of the fiber composite. The shot particles may then fall on the material being burned and pollute the material.
Fibers of the above-mentioned type can also be used in isolated frameworks. With strong vibrations, shot particles between the fibers can lead to the destruction of the framework formed by the fibers. This has an especially negative effect on catalytic packings or particle filter packings in the exhaust gas system of a motor vehicle.
Shot particles remaining in uncleaned fibers can also have a negative impact on components that are manufactured from the fibers. If the components need to be remachined at some point, the coarser, non-fibrous shot particles may break out of the component during the machining, e.g. by sawing, cutting, grinding etc. Such breakout can leave behind undesired surface defects in the remachined component.
It has been found that a direct dry screening of the fiber agglomerate is inefficient and ineffective. Far too few of the fibers in the fiber agglomerate exhibiting the desired fiber dimensions are separated from the fiber agglomerate. Furthermore, a high percentage of undesirable fiber fragments are produced.
Wet disintegration of fiber agglomerates and separation of fibers from coarser, non-fibrous shot particles has been conducted by means of varying rates of sedimentation in a liquid medium. However, it is very time consuming and thus is very expensive. Furthermore, this process is not sufficiently accurate, because large quantities of otherwise usable fibers are discarded along with the coarser particles.